Prior parking meters are known which increase revenues by detecting the presence or absence of a vehicle. For example, U.S. Pat. No. 4,823,928 describes an electronic parking meter system that resets the timing circuit to zero when a vehicle is no longer detected in the associated parking space. Such parking meter is placed into operational mode when a coin or other payment method is input into the meter. Then a sonar range finder is turned on to detect the presence or absence of a vehicle in the associated parking space. The sonar range finder is also used to provide a signal to a microprocessor controller when the vehicle is no longer in the associated parking space. The microprocessor controller then resets the timer.
The above-noted parking meter system may improve revenue, but it does not capture parking meter violations. Therefore it does not optimize revenue or provide a deterrent for parking violators because there are few parking meter attendants to police the many metered spots in any given jurisdiction. Employing more meter attendants is not a cost-effective solution either. This problem was addressed by the parking meter of U.S. Pat. No. 5,777,951.
The device of U.S. Pat. No. 5,777,951, which is hereby incorporated by reference in its entirety, is a parking meter system including a camera to record and store the image of the license plate of a parking violator. The parking meter includes a microcontroller and a timer coupled with the microcontroller. The payment acceptance means is coupled with the microcontroller for accepting payment for use of an associated parking space. The microcontroller initiates the timer for a prepaid parking interval upon receiving a signal from the payment acceptance means. A vehicle detection means is coupled with the microcontroller for detecting the presence or absence of a vehicle in the associated parking space. A communications modem is coupled with the microcontroller. The microprocessor initiates a camera to take an image of a vehicle upon the vehicle detection means signaling to the microprocessor the presence of the vehicle in the associated parking space after the timer has signaled to the microprocessor the expiration of the prepaid parking interval.
U.S. Pat. Nos. 7,029,167 and 7,393,134, both of which are hereby incorporated by reference in their entirety, disclose improvements to the device of U.S. Pat. No. 5,777,951. However, in both of these patents, the microcontroller initiates an interrogation station to direct an interrogation signal at the associated parking space in the area of the parking space where the license plate of a parked vehicle is located upon determining the existence of a parking violation.
Taking pictures of the vehicle or its license plate after determining a violation can be unreliable because an unacceptably high number of violations may not be caught if a violation cannot be determined before the vehicle leaves the camera's field of view. Therefore, there remains a need for improved parking meter systems that addresses some or all of the drawbacks in the prior art.